// Permutations in js reference (also cool algorithm):
// https://stackoverflow.com/a/41068709
function perm(a){
    if (a.length == 0) return [[]];
    var r = [[a[0]]],
        t = [],
        s = [];
    if (a.length == 1) return r;
    for (var i = 1, la = a.length; i < la; i++){
        for (var j = 0, lr = r.length; j < lr; j++){
            r[j].push(a[i]);
            t.push(r[j]);
            for(var k = 1, lrj = r[j].length; k < lrj; k++){
                for (var l = 0; l < lrj; l++) s[l] = r[j][(k+l)%lrj];
                t[t.length] = s;
                s = [];
            }
        }
        r = t;
        t = [];
    }
    return r;
}

function setHTML(id, html) {
    document.getElementById(id).innerHTML = html;
}

function setValue(id, value) {
    let el = document.getElementById(id);
    el.value = value;
    el.dispatchEvent(new Event("change"));
}

// Base 64 encoding tools
// https://stackoverflow.com/a/27696695
// Modified for fixed precision

Base64 = (function () {
    var digitsStr = 
    //   0       8       16      24      32      40      48      56     63
    //   v       v       v       v       v       v       v       v      v
        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+-";
    var digits = digitsStr.split('');
    var digitsMap = {};
    for (var i = 0; i < digits.length; i++) {
        digitsMap[digits[i]] = i;
    }
    return {
        fromIntV: function(int32) {
            var result = '';
            while (true) {
                result = digits[int32 & 0x3f] + result;
                int32 >>>= 6;
                if (int32 === 0)
                    break;
            }
            return result;
        },
        fromIntN: function(int32, n) {
            var result = '';
            for (let i = 0; i < n; ++i) {
                result = digits[int32 & 0x3f] + result;
                int32 >>>= 6;
            }
            return result;
        },
        toInt: function(digitsStr) {
            var result = 0;
            var digits = digitsStr.split('');
            for (var i = 0; i < digits.length; i++) {
                result = (result << 6) + digitsMap[digits[i]];
            }
            return result;
        },
    };
})();

// Base64.fromInt(-2147483648); // gives "200000"
// Base64.toInt("200000"); // gives -2147483648